Tool for cleaning and burnishing commutators



Sept. 17, 1957 J. c. HEAD 2,306,333

TOOL FOR CLEANING AND BURNISHING COMMUTATORS Filed April 25, 1956 Ems/ 23W Jmmss 62/1245: 62/70 United States Patent TOOL FOR CLEANING AND BURNISHING COMlVIUTATORS James Charles Head, Kenora, Ontario, Canada Application April 23, 1956, Serial No. 579,798

6 Claims. (Cl. 51-205) This invention relates to the art of metal burnishing and more particularly to a device which is especially designed as a tool for effectively cleaning and burnishing the commutators of small and medium sized electric generators, motors and rotating direct current transformers without scarring the'faces of the commutator segments.

Hitherto the principal method employed to clean a commutator has been manual abrasion with a sandpaper or like abrasive. This is generally a slow and unsatisfactory procedure and, if the commutator is situated in an inaccessible position, may be an ineificient and awkward one as well. On occasion when the commutator has accumulated a quantity of foreign matter on its segments, a sharp instrument such as a chisel is often used in an attempt to peel or chip away the undesirable coating. This common practice frequently results in scarring of the surface of the commutator segments.

It is an object of the present invention to provide a tool for eificiently cleaning and burnishing the segments of a commutator.

It is a further object of the present invention to provide a useful tool for cleaning and burnishing, without scarring, the segments of a commutator while the commutator rotates in its normal relationship to the other parts of the generator, motor or transformer, as the case may be.

A still further object of the invention is to provide a useful tool for cleaning and burnishing the segments of a commutator inaccessibly situated for easy cleaning by known methods.

Another object of the invention lies in the simplicity, strength, durability and efliciency which is displayed by the device.

A further object of the invention is to provide a new and useful method of cleaning and burnishing the segment faces of a commutator.

Other objects and advantages of the invention will become apparent in the light of the following description, reference being had to the: accompanying drawings wherein:

Figure l is a plan view of the commutator burnishing tool;

Figure 2 is an exploded plan view of the said tool with certain portions cut away to illustrate features of construction;

Figure 3 is a perspective view of a portion of the said tool showing the operation of the self-contained reforming means;

Figure 4 is a perspective view of the upper end of the handle of the said tool;

Figure 5 is a diagram illustrating the preferred method of using the tool to clean and burnish the segment faces of a commutator.

By reference to the drawings it will be seen that the tool which I have invented comprises three principal components, a rod 1, one end of which, when the tool is in use, contacts the part to be cleaned and burnished, a handle 2, and a top or cap portion 3, removable from 2 the handle by direct upward pull, in a manner and for a purpose to be described hereinafter.

The rod portion, 1 is cut from stock, preferably circular in cross section, of a glass fiber reinforced plastic. One end of the rod 1 is rounded to form a tip 4.

The handle 2 is formed from any suitable material, preferably a non-brittle relatively insoluble plastic such: as nylon. The handle may be formed either circular in cross section, as shown in Figure 4 of the drawings hereto, or square or irregular in shape. It may be grooved to permit easy grasping. One end of the handle is recessed to form a socket 5 for receiving and holding the end of rod 1 which is remote from the rounded tip 4. The socket 5 is of shape and size to conform with the end of the rod which it is to receive. The rod may be firmly cemented into the socket 5 in the handle, or alternatively, if the diameters of rod and socket are machined with close tolerance, the parts can be forced together to be held tightly by friction. Where a plastic is used to form the handle 2, it may be found practical to hot-mold the handle around the rod 1, in which case the socket 5 becomes an automatic bond to the rod.

The upper end 6 of the handle 2 is both slotted and chambered as shown in Figures 2 and 4. The chamber, designated generally by the numeral 7, has a tapered inner surface 8 which acts to hold the cap 3 in the chamber of the handle when the cap is not in use. A slot 9 is positioned across the upper end 6 of the handle, dividing the said end into two halves 10. Under pressure these halves 10, which form the walls of the chamber 7, will spread apart slightly and allow the base of the cap 3 to be inserted into the said chamber. On releasing this pressure, the halves 10 close upon the base 11 of the cap in a snug lock, due to the corresponding tapers on the chamber Walls and base of the cap.

The top portion of the tool or cap, designated by the numeral 3, may be formed of the same material from which the handle of the tool is made. The base 11 of the cap is tapered and dimensioned to fit snugly within the chamber '7 in the top of the handle. A semi-spherical recess 12 is set in the bottom surface ll of the cap. This recess is coated with a thin film of cement and while the cement is still in a wet state, abrasive particles, for example particles of Carborundum, a compound of carbon and silicon, are sprinkled thereon. Use of this abrasive-lined recess to reform the tool tip 4 is described below.

Various types of glass fiber reinforced plastic compositions have been fabricated in rod form and are effective for the purposes of this invention. In the forms more commonly available commercially, the glass fiber is present in the rod either as chopped strands or as roving and has a fiber diameter ranging from 0.00020 to 0.00100 inch. Most commonly thermosetting resins are used. Such resins include phenolic, melamine, polyester, epoxy, silicone and furane resins. Although all of these glass fiber reinforced plastic compositions are effective for the purpose of this invention, I prefer, because it is readily available commercially and relatively inexpensive, a rod of glass fiber reinforced polyester resin. Such rods are available from various manufacturers. By way of example, I mention as a suitable material a glass reinforced plastic rod stock manufactured by Smith & Stone Limited of Georgetown, Ontario, Canada, using glass fiber marketed by Fiberglas Canada Limited of Toronto, Canada under the name Fiberglas Plastics Reinforcing Roving and a low viscosity, highly reactive polyester resin manufactured and sold by American Cyanamid Company of New York City under the trade name Laminac 4128.

In the use of the device, the tool tip 4 is held, with light to moderate pressure, against the commutator segments, while the unit to be cleaned and burnished is to tated at its normal rate of revolutions per minute. The tool is held in the hand] in much the same manner as one would hold a writing pen. To clean the segments of the commutator the tool is moved from side to side across the commutator segments as the commutator revolves. The very fine glass fibers which compose the rod clean the metal segments by abrasion. As the tool is moved across the commutator segments in a surface to surface relationship, the portion of the tool tip in con tact with the rotating commutator will acquire a thin smooth film of metal particles. This coating on the tip of the tool tends to burnish each segment of the rotating commutator to'a high lustre finish. It has been found that best results are obtained when the tool is held in contact with the commutator for periods not longer than five seconds at a time, using light to moderate pressure. Excessive pressure will not spec-d the operation. If this first cleaning is unsatisfactory, the tool may be rotated to a clean spot on the tip and the process repeated.

The glass fiber reinforced plastic from which the rod is made is an excellent electrical insulator and prevents electrical discharge from reaching the body of the user of the tool. Furthermore the inherent properties of these compositions give the tool high strength, durability and chemical resistivity.

The preferred Working angle of the tool is illustrated in Figure 5, where XX represents the true horizontal base upon which the unit to be cleaned is set and YY the true vertical to the horizontal level. Ideally the tool tip 4 is set on the commutator 13 just past the vertical YY so that the tool tip is resting on a false vertical, marked ZZ for the purpose of illustration. The Working angle between the tool and the line ZZ is approximately 55. If the working angle is substantially less than 55, too much tip is used and a ragged chatter will be felt in the tool. To the other extreme, if the working angle i too large there is a danger that the side of the glass fiber reinforced plastic rod will ride on the commutator and be injured through the tearing of fiber shreds from the side of the rod by the joints between individual commutator segments.

If the tip of the tool 4 becomes plated in excess or worn out of the round, it may be reformed by use of the cap 3 of the tool, as illustrated in Figure 3. An upward pull of the cap 3, which in the illustrated form has been shown with a rounded upper portion 14 for easy grasping, will, due to the tapering surfaces on the chamber 7 of the handle and the base 11 of the cap, spread the sides of the chamber and release the cap. The tip 4 of the rod may then be inserted into the recess 12 in the bottom surface of the cap. By twisting the tip of the rod against the abrasive lining of the recess 12,

F the tip of the tool may be restored for further use. The

cap 3 may then be snapped back into the chamber in the handle of the tool to be retained there until a further reforming of the tool tip becomes necessary.

It is to be understood that the invention is not limited to the precise form shown, but that it includes within its purview, whatever changes fairly come within either the terms or scope of the appended claims.

I claim:

1. A tool adapted for cleaning and burnishing commutators comprising a rod of glass fiber reinforced plastic, rounded at one end, in combination with a handle provided with removable abrasive means for reforming the rounded end of the said rod, said handle being rigidly secured to the other end of the rod.

2. A tool adapted for cleaning and burnishing commutators comprising a rod of glass fiber reinforced plastic, rounded at one end, in combination with a handle rigidly secured to the other end of the said rod, and a cap for the handle, the base of which cap is removably insertable into a chamber in the upper end of the said handle, said base being provided with an abrasive-lined recess.

3. The tool of claim 1 in which the plastic is a thermosetting resin.

4. The tool of claim 3 in which the thermosetting resin is a polyester resin. 1

5. The tool of claim 2 in which the plastic is a thermosetting resin.

6. The tool of claim 5 in which the thermosetting resin is a polyester resin.

References Cited in the file of this patent UNITED STATES PATENTS 

